EP0707017B1 - Process for preparing diene rubber obtained with a Nd-catalyst and having improved cold flow and reduced odour - Google Patents

Description

The invention relates to a method for producing by means of Nd catalysts polymerized diene rubbers with low cold flow and low intrinsic odor.

The production of polydienes, e.g. of cis-polybutadiene (BR) based on Ziegler-Natta catalysts has long been an industrial process. Depending on the catalyst metal used, there is commercially available Ti-BR, Co-BR, Ni-BR and Nd-BR. Products and processes have different specific ones Advantages and disadvantages. For example, in some manufacturing processes the polymerization temperatures are kept low by cooling (isothermal Driving style) to suppress unwanted side reactions that lead to Gelation of the reactors or deterioration of product properties would. Such processes are less energy efficient than adiabatic ones Polymerizations in which the heat of polymerization released is used, to heat the polymerization solution.

In European patent application 0 011 184 there are mixed organometallic catalysts described on the basis of neodymium carboxylates, which in particular suitably used in the solution polymerization of conjugated dienes can be. The according to European patent application 0 011 184 Polydienes produced, especially polybutadiene, have a particular favorable property profile. Disadvantageous in the polymerization of dienes with However, the catalysts mentioned is that the polymers have a relatively high cold flow possess, which can lead to problems with storage and transport. It is Although known that the catalyst effect by preforming Nd catalysts can be changed. Such preformed Nd catalysts provide Polymers with a relatively low cold flow, but decreases due to preforming the catalyst activity, so that the consumption of neodymium is sometimes considerable increases.

It is also known that polydienes with improved properties, in particular low cold flow, can be produced if one follows the diene polymers polymerization with disulfur dichloride, sulfur dichloride, thionyl chloride, Treated disulfur dibromide or thionyl bromide (see DE-AS 1 260 794). A disadvantage of the manufacturing process described in DE-AS 1 260 794 rubber-elastic diene polymer with improved properties however, that the diene polymers obtained have an unpleasant smell, which interferes with the processing of these diene polymers.

From US-A-4,533,711 the production of butadiene rubber mixtures is known which have an improved "green strength". The polybutadienes described there are produced in a two-stage polymerization process, a catalyst system based on rare earth compounds being used. According to the statements in column 4, lines 29-30, the second stage of the polymerization process can be carried out in an adiabatic manner. The US patent says nothing about improving the cold flow and the inherent odor of polybutadiene.
The object of the present invention is therefore to provide a process which provides diene rubbers in an energetically favorable way, with good rubber properties, low cold flow and no unpleasant odor.

The present invention therefore relates to a method for producing means Nd catalysts polymerized diene rubbers with low cold flow and low intrinsic odor, which is characterized in that diolefins in In the presence of inert, organic solvents and in the presence of organometallic Mixed catalysts based on neodymium carboxylates in adiabatic Polymerized at temperatures from -20 ° C to 150 ° C, then the reaction mixture thus obtained is released by reducing the pressure and then the reaction mixture with disulfide dichloride, sulfur dichloride and / or treated with thionyl chloride.

Butadiene, isoprene, pentadiene can be used as dienes in the process according to the invention and 2,3-dimethylbutadiene are used, in particular butadiene and isoprene. The dienes mentioned can be used individually or in a mixture with one another are used so that either homopolymers or copolymers of the mentioned services arise.

The polymerization according to the invention is carried out in the presence of inert, organic Solvents. Examples of inert organic solvents are in question: aromatic, aliphatic and / or cycloaliphatic hydrocarbons, such as benzene, toluene, pentane, n-hexane, iso-hexane, heptane and / or Cyclohexane.

The inert, organic solvents are used in amounts of 200 to 900 parts by weight, based on 100 parts by weight of monomers. Are preferred Quantities from 400 to 700 parts by weight.

A) einem Carboxylat des Neodyms der Formel

B) einem Aluminiumalkyl Al R₃ ⁴ oder R₂ ⁴Al H

C) einer Lewis-Säure, wobei in den Formeln

R¹, R² und R³

gleich sind oder verschiedene Alkylreste mit 1 bis 10 Kohlenstoffatomen bedeuten, wobei die Summe aller C-Atome in den Substituenten 6 bis 20 beträgt, und

R⁴

einen Alkylrest mit 1 bis 10 Kohlenstoffatomen bedeutet.

It is important for the process according to the invention that the neodymium catalysts used are those neodymium catalysts as described in the aforementioned European patent application 0 011 184. The neodymium catalysts to be used accordingly consist of:

A) a carboxylate of the neodymium of the formula

B) an aluminum alkyl Al R ₃ ⁴ or R ₂ ⁴ Al H

C) a Lewis acid, wherein in the formulas

R ¹ , R ² and R ³

are the same or different alkyl radicals having 1 to 10 carbon atoms, the sum of all carbon atoms in the substituents being 6 to 20, and

R ⁴

represents an alkyl radical having 1 to 10 carbon atoms.

A) Neodym(versatat)₃,

B) Diisobutylaluminiumhydrid (DIBAH),

und

C) Ethylaluminiumsesquichlorid (EASC).

In particular, catalysts are used in the process according to the invention, which consist of, for example:

A) Neodymium (versatat) ₃ ,

B) diisobutyl aluminum hydride (DIBAH),

and

C) Ethyl aluminum sesquichloride (EASC).

In the polymerization according to the invention, the organometallic according to the invention becomes Mixed catalyst based on neodymium carboxylates in quantities of 0.001 to 0.15, based on 100 parts by weight of monomer, is used, in particular in Amounts from 0.05 to 0.10 parts by weight.

The process according to the invention is preferred in an adiabatic manner at temperatures from -20 to 130 ° C. Ask for adiabatic driving pressures of approx. 1 to 7 bar.

After the polymerization has ended (conversion: ≥ 98%), this will be the reaction mixture thus obtained is relaxed by reducing the pressure. Here can be relaxed to normal pressure; for technical reasons the pressure reduced to 1.1 to 1.6 bar. All low boilers evaporate during relaxation Components of the reaction mixture, such as unreacted dienes.

The reaction mixture remaining after the expansion, which is now practical is free of low-boiling fractions, is mixed with disulfide dichloride, sulfur dichloride and / or treated with thionyl chloride. Treatment with is preferred The sulfur di chloride is carried out.

Generally 0.05 to 0.5 part by weight, preferably 0.1 to 0.4 part by weight Sulfur chlorides per 100 parts by weight of diene rubber added.

The treatment with the sulfur chlorides is usually carried out at temperatures from 20 to 150 ° C, preferably at 40 to 60 ° C.

In the process according to the invention, the sulfur chlorides mentioned stirred for about 5 to 30 minutes with the reaction mixture, after which the reaction mixture worked up by using the solvent in the usual way Stripped water vapor and dries the water-moist crumbs, e.g. with a Sedge snail and downstream hot air dryer.

According to the method according to the invention, it is particularly advantageous possible, the diene rubbers obtained together with the sulfur chlorides Extender oils such as aromatic extender oils to add. It succeeds in the Mooney viscosity of the rubbers in a way that is suitable for processing Set values from 30 to 50. The appropriate amount of extender oil depends on the desired Mooney viscosity of the diene rubbers and can easily be determined by appropriate preliminary tests. 20 to 50 phr (phr = per hundred rubber).

It is particularly surprising that the process according to the invention only succeeds if in adiabatic driving style with subsequent relaxation of the reaction mixture the polymerization in the presence of the in the European patent application 0 011 184 described organometallic mixed catalysts performed becomes.

Good results regarding the cold flow are obtained if, for example polymerized with titanium catalysts (see comparative example). The so produced However, products usually have a strong intrinsic odor.

The method according to the invention has the following advantages:
Production of polydienes with a highly stereospecific cis-1,4 structure and good product properties using an adiabatic polymerization process in which the reaction leads to high conversions. The subsequent relaxation and reaction with sulfur compounds result in products with a low cold flow and their own smell.

Examples

In the following examples the cold flow is given in (mg / min). He was determined using a modified outflow plastometer at 50 ° C. This method is largely adapted to the conditions in practice.

Comparative Example 1

This example corresponds to the prior art, the polymerization using a titanium catalyst is carried out.

1. Triethylaluminium (TEA), 1,35 mmol phm (per hundred monomer)

2. Titanethoxitriiodid (TEI), 0,15 mmol phm

3. Titantetrachlorid (TTC), 0,15 mmol phm.

A cascade of 4 stirred polymerization reactors is fed continuously with a stream of butadiene, dissolved in benzene (12%). Temperature of the monomer solution 4 ° C. The polymerization is started by adding the following catalyst components:

1. Triethyl aluminum (TEA), 1.35 mmol phm (per hundred monomer)

2. Titanethoxitriiodide (TEI), 0.15 mmol phm

3. Titanium tetrachloride (TTC), 0.15 mmol phm.

The solution is kept at temperatures of ≤ 50 ° C. by cooling. At about 95% The reaction is converted by adding 0.65 phm stearic acid and 0.27 phm Vulkanox BKF stopped. The solution is heated to about 130 ° C and in promoted a flash tank, with unreacted butadiene and a Part of the solvent evaporates so that the polymer concentration to 15% increases. The solution is treated with steam so that the solvent Will get removed. This creates a crumb suspension, which according to the state of the Technology is processed by dewatering and drying to the finished product.

The product has the following properties: ML 1 + 4/100 ° C: 47. Cold flow 18 mg / min.

Comparative Example 2

Katalysatordosierung

TEA: 1,5 mmol phm
TEI: 0,2 mmol phm.
TTC: 0,2 mmol phm.

This example corresponds to the 1st comparative example with the following difference:

Catalyst dosing

TEA: 1.5 mmol phm
TEI: 0.2 mmol phm.
TTC: 0.2 mmol phm.

This produces a product with ML of 37. After evaporation of the residual monomer with 0.085 phr S ₂ Cl _2, this product is stirred for about 30 minutes. The product, which is then processed in the usual way, has the following properties:
ML-1 + 4/100 ° C: 47. Cold flow 4 mg / min.

The cold flow is significantly reduced, but the product now has one clear smell, which is perceived as annoying.

Example according to the invention

1. Diisobutylaluminiumhydrid (DIBAH), 0,150 g phm

2. Ethylaluminiumsesquichlorid (EASC), 0,03 g phm

3. Neodymversatat (NdV), 0,08 g phm.

A cascade of 3 stirred reactors is fed continuously with a stream of butadiene, dissolved in hexane (17%). Temperature of the monomer solution 0 ° C. The polymerization is started by adding the following catalyst components:

1. Diisobutyl aluminum hydride (DIBAH), 0.150 g phm

2. Ethyl aluminum sesquichloride (EASC), 0.03 g phm

3. Neodymium Versatat (NdV), 0.08 g phm.

The polymerization runs adiabatically, so that after> 99% conversion has been reached, the temperature is approximately 110.degree. The catalyst is deactivated by adding 0.5 phm stearic acid, at the same time a solution of stabilizer (0.4 phm TNPP / 0.2 phm Irganox 565) is added. The pressure, which had previously been approximately 5 to 7 bar, is reduced to 1.5 bar in a flash tank, with low-boiling components and solvents evaporating. This increases the concentration of the product in the solvent to 18%. This solution is stirred with 0.10 phm S ₂ Cl _{2 for} about 30 minutes, after which it is worked up in the usual way.

The product has the following characteristics:
ML 1 + 4/100 ° C: 44, cold flow 10 mg / min.

There is no annoying smell.

Comparative Example 3

This example is carried out like the example according to the invention with the difference that the polymer solution is not concentrated by relaxation before reaction with S ₂ Cl ₂ . A product as in the invention is obtained, but a distinct intrinsic odor can still be determined.

Claims (3)

1. A process for producing diene rubbers polymerised by means of Nd catalysts and exhibiting reduced cold flow and low intrinsic odour, characterised in that diolefines are polymerised adiabatically at temperatures of -20°C to 150°C in the presence of inert organic solvents and in the presence of metallo-organic mixed catalysts based on neodymium carboxylate, the reaction mixture obtained in this manner is subsequently depressurised by reducing the pressure, and thereafter the reaction mixture is treated with disulphur dichloride, sulphur dichloride and/or thionyl chloride.
2. A process according to claim 1, characterised in that the diolefines are polymerised adiabatically at temperatures of -20 to 150°C in the presence of inert aromatic, aliphatic and/or cycloaliphatic hydrocarbons and in the presence of 0.001 to 0.15 parts by weight, based on 100 parts by weight of monomer, of metallo-organic mixed catalysts based on neodymium carboxylate, the reaction mixture obtained in this manner is subsequently depressurised by reducing the pressure and thereafter the reaction mixture is treated with 0.05 to 0.5 parts by weight, based on 100 parts by weight of diene rubber, of disulphur dichloride, sulphur dichloride and/or thionyl chloride.
3. A process according to claims 1 or 2, characterised in that the reaction mixture is treated with disulphur dichloride.